Version 4.0.3-alpha

Version 3.0.5

Good news! We've had some "at-scale" with over 100 people online simultaneously. I'm pleased to report that after fixing some performance issues in 4.1.10, Orebfuscator 4.1.14 until latest consumes less then 0.05% of tick time with 100+ players on a fairly modest server machine. You cannot beat that kind of performance, with this feature set, at that kind of load.

That said, if you run a larger server (100+ players), we'd be especially grateful if you could share your timings report with us.

The performance is only higher in cases of random access. Seek performance might be superior in an RDBMS, but as the cache is regionalized the same way the Minecraft map is, and region/chunks are loaded into memory en-masse, there is likely no benefit from the improved random access performance of an RDBMS and no benefit at all from its indexing ...

I don't want to get into a lengthy back and forth over caching here, but long story short -- the cache is loaded into memory; locality wins, so having the cache local on the disk will always beat network/remote (database) performance; RDBMS's advantages are nullified in this specific use case due to architecture considerations; the only way OP can achieve freedom is purchasing a larger disk (regrettably), or leveraging the suggestion I made concerning throwing away older cache regions as they age out.

Hope that helps clarify! Don't be confused by RDBMS; it is not a fix all. In this case it'd just be moving locality off disk and onto network, with an overall reduction in performance (assuming your RDBMS was on a different physical box). If your RDBMS was on the same box, everything would just get worse in total.

Currently this plugin obfuscates all ores on my server, but I am not happy with cpu load during travelling with elytra. How much lower will be the load on cpu from orebfuscator if I will obfuscate only diamond, lapis and gold?

Hard to predict exactly; Can you share some timings with us of your CPU under load with Elytra, demonstrating where Orebfuscator is taking a long time? We could use that information to improve the plugin.